1. Field of the Invention
This invention relates to a flexible printed circuit film, and more particularly to a flexible printed circuit film that is capable of preventing a bonded pad from being separated or opened due to a tension applied to a bonded part when the flexible printed circuit film is engaged to a printed circuit board.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) module controls light transmissivity in accordance with an electric field to thereby display a picture corresponding to video signals. To this end, the liquid crystal display module includes a liquid crystal display panel having a plurality of pixels arranged in a matrix and a driving circuit for driving the liquid crystal display panel.
Each pixel arranged on the liquid crystal display panel includes a liquid crystal cell positioned at an intersection between a gate line and a data line, and a thin film transistor (TFT) for selectively connecting the liquid crystal cell to the data line in response to a signal on the gate line. The driving circuit for driving the liquid crystal display panel consists of a data driving integrated circuit (IC) for driving the data lines on the liquid crystal display panel, a gate driving IC for driving the gate lines on the liquid crystal display panel, and a control circuit for controlling the gate driving IC and the data driving IC. These driving IC's usually take the shape of a chip and are mounted in a tape carrier package (TCP) in the case of a tape automated bonding (TAB) system, or on the surface of the liquid crystal display panel in the case of a chips on glass (COG) system.
In the case of the TAB system, the driving IC's are electrically connected to a pad provided at the liquid crystal display panel by the TCP. For instance, in the LCD module of a TAB system, as shown in FIG. 1, the rear side of a liquid crystal display panel 1 is provided with a timing control board 6, a data circuit board 4, flexible printed circuit (FPC) film 12 and a gate circuit board 2. Data driving IC chips 10 are loaded in a TCP 8 to be connected, via the TCP 8, to the liquid crystal display panel 1 and the data circuit board 4. Gate driving IC chips (not shown) also are loaded in the TCP 8 to be connected, via the TCP 8, to the liquid crystal display panel 1 and the gate circuit board 2. The data circuit board 4 is connected, via the FPC film 12, to the timing control board 6 to relay a data transmission between the timing control board 6 and the data driving IC chips 10. The gate circuit board 2 also is connected, via a FPC film (not shown), to the timing control board 6 to relay a signal transmission between the timing control board 6 and the gate driving IC chips.
The FPC film 12 connected between the data circuit board 4 and the timing control board 6 usually has an “L” shape. The timing control board 6 applies a data control signal, which includes a data signal and a synchronizing signal, etc., via the FPC film 12, to the data circuit board 4. Further, the timing control board 6 applies a gate control signal, which includes a synchronizing signal, etc., via the FPC film (not shown), to the gate circuit board 2. The TCP 8 loaded with the data driving IC chips 10 is electrically connected to one pad area of the liquid crystal display panel 1 and, at the same time, one edge of the data circuit board 4. In a similar manner, the TCP loaded with the gate driving IC chips also is electrically connected between the liquid crystal display panel 1 and the gate circuit board 2.
The FPC film 12 includes a first pad 16 for connecting to a pad of the data circuit board 4, and a second pad 18 for connecting to the timing control board 6. The first pad 16 is adhered to the pad of the data circuit board 4 by an anisotropic conductive film. The second pad 18 of the FPC film contacts a connecter 14, which is provided at one end of the timing control board 6. To engage the second pad 18 of the FPC film 12 with the connecter 14, force is applied from the exterior to the connecter 14 in the “A” direction toward the second pad 18, as shown in FIG. 2. At this time, force is transferred via a body of the FPC film 12, into the first pad 16. Thus, a contact portion between the first pad 16 and the pad of the data circuit board 4 is separated or opened by the force transferred to the first pad 16. This causes a serious problem of an electrical breakage between the timing control board and the data circuit board.